Solder bonding technique for assembling a tilted chip or substrate
AssigneeJDS Uniphase Corporation
InventorsPhilip Deane, Neil Teitelbaum
Life of this patent
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Abstract
A method for solder bonding a photodiode or an array of photodiodes to a substrate, the photodiode(s) tilted at a predetermined angle, uses a pair solder bumps placed on a photodiode chip opposite a corresponding pair of solder pads placed on the substrate. When the photodiode chip is placed on the substrate, with the solder bumps therebetween, the solder is melted and undergoes a reflow over the surface of the pads. The shape of the pads and the location of the solder bumps on the pads causes the surface tension of the solder to tilt the chip by pulling it to one side.
Claims17
A method of bonding an element to a substrate, the method comprising the steps of:
- a) providing a substrate having a generally flat surface,
- b) placing two or more solder bumps having a predetermined volume on either the substrate or on the element, the bumps defining a single axis,
- c) determining a shape, size and location of two or more solder pads on the other of the substrate or element so as effect a predetermined orientation of the element at a predetermined angle with respect to the substrate during heating and melting of the solder bumps,
- d) effecting a contact of the element with the substrate via the solder bumps, such that the element is supported on the solder bumps only in a first supported position, and
- e) after step (d) heating the solder bumps in the absence of any further supporting or orienting of the element to cause a flow of the solder bumps and to cause a predetermined tilting displacement of the element by gravity forces and by surface tension forces substantially about the axis defined by the solder bumps so as to re-orient the element at a predetermined angle in a second secured position between angles greater than 0 and less than 90 degrees with respect to the substrate by said heating alone.
A method of bonding an element to a substrate, the method comprising the steps of;
- a) providing a substrate having a generally flat surface,
- b) placing two or more solder bumps having a predetermined volume on either the substrate or on the element, the bumps defining a single axis,
- c) providing at least two pads on the other of the substrate or the element for contacting with the solder bumps placed in step (b) wherein the size and location of two or more solder pads on the other of the substrate or element is selected so as effect a predetermined orientation of the element at a predetermined angle with respect to the substrate during heating and melting of the solder bumps, the shape of the pads being asymmetric about the single axis when a contact is made between the substrate and the element,
- d) effecting the contact of the element with the substrate via the solder bumps, such that the element is secured to and supported on the solder bumps only, and
- e) after step (d) heating the solder bumps in the absence of any further supporting or orienting of the element to cause a flow of the solder bumps and to cause a predetermined tilting displacement of the element by gravity force and by surface tension force substantially about the axis defined by the solder bumps so as to orient the element at a predetermined angle between and including angles of 0 and 90 degrees with respect to the substrate by said heating alone.
Dependencies are inferred from the claim text.